I'm not sure what the altimeter is? If you are refering to the Voltmeter then I'm with you, the only temp. gauge on the 81 is for the engines temp...There's no outside air temp gauge on the bike that I'm aware of , perhaps yours has one but I'd like to see a photo of it...

The Interstates came from Honda with optional gauges in place of the radio/CB displays: a voltmeter, air temperature gauge, altimeter, and clock.

The temperature gauge has a long, thin piece of metal that goes from the gauge down to the front of the fairing, in order to read outside temperature instead of the temperature inside the fairing. Unfortunately this long thin piece of metal is also quite fragile and easily broken, rendering the temperature gauge inoperative. More than likely that's what's happened to yours.

Ah Man, mine doesn't have all that cool stuff, that's awesome of you to post a photo, I want that now I'm jealous again that's pretty slick man..Freakin auto gauges it looks like, I only have a voltmeter and a stupid lighter I never use cuss I don't smoke, voltmeter is like really old looking too.. still works though..

Took my wing up on a mountain pass this last weekend and found that the altimeter is accurate. You can turn the face of the gauge to "calibrate" the gauge. Works like a champ!! Still haven't gotten the temp. gauge to work yet. I think I need a thermocouple for it, any ideas??

I have the same guages on my 83 Interstate, the temp gauge has a rubber hose with a very thin and delicate brass tube inside it connecting it to a metal bulb under the fairing. This bulb/tube has some kind of pressurised gas inside it that expands/contracts with temp change and moves the guage needle. I was working on the guage wiring and bent the tube one too many times and it broke... Hissed and released a cloud. And that was the end of that gauge.

I doubt it could be repaired but you never know, I replaced mine with a Cyberdyne digital guage from eBay.